Question

执行“ng build”命令时发生错误：

ERROR in src/app/model/rest.datasource.ts(34,5): error TS2322: Type 'Observable<Product | Order | Product[] | Order[]>' is not assignable to type 'Observable<Product[]>'.
  Type 'Product | Order | Product[] | Order[]' is not assignable to type 'Product[]'.

文件rest.datasource.ts：

import { Injectable } from '@angular/core';
import { Http, Request, RequestMethod } from '@angular/http';
import { Observable } from 'rxjs/Observable';
import { Product } from './product.model';
import { Cart } from './cart.model';
import { Order } from './order.model';
import 'rxjs/add/operator/map';

const PROTOCOL = 'http';
const PORT = 3500;

@Injectable()
export class RestDataSource {
  baseUrl: string;
  auth_token: string;

  constructor(private http: Http) {
    this.baseUrl = `${PROTOCOL}://${location.hostname}:${PORT}/`;
  }

  authenticate(user: string, pass: string): Observable<boolean> {
    return this.http.request(new Request({
      method: RequestMethod.Post,
      url: this.baseUrl + 'login',
      body: {name: user, password: pass}
    })).map(response => {
      let r = response.json();
      this.auth_token = r.success ? r.token : null;
      return r.success;
    });
  }

  getProducts(): Observable<Product[]> {
    return this.sendRequest(RequestMethod.Get, 'products');
  }

  saveProduct(product: Product): Observable<Product> {
    return this.sendRequest(RequestMethod.Post, 'products', product, true);
  }

  updateProduct(product): Observable<Product> {
    return this.sendRequest(RequestMethod.Put, `products/${product.id}`, product, true);
  }

  deleteProduct(id: number): Observable<Product> {
    return this.sendRequest(RequestMethod.Delete, `products/${id}`, null, true);
  }

  getOrders(): Observable<Order[]> {
    return this.sendRequest(RequestMethod.Get, 'orders', null, true);
  }

  deleteOrder(id: number): Observable<Order> {
    return this.sendRequest(RequestMethod.Delete, `orders/${id}`, null, true);
  }

  updateOrder(order: Order): Observable<Order> {
    return this.sendRequest(RequestMethod.Put, `orders/${order.id}`, order, true);
  }
  saveOrder(order: Order): Observable<Order> {
    return this.sendRequest(RequestMethod.Post, 'orders', order);
  }

  private sendRequest(verb: RequestMethod, url: string, body?: Product | Order, auth: boolean = false)
    : Observable<Product | Product[] | Order | Order[]> {

    let request = new Request({
      method: verb,
      url: this.baseUrl + url,
      body: body
    });
    if (auth && this.auth_token != null) {
      request.headers.set('Authorization', `Bearer<${this.auth_token}>`);
    }
    return this.http.request(request).map(response => response.json());
  }
}

终端错误： Error TS2322

帮助我理解，这是代码中的错误还是编译错误？

PS：执行“ng serve”命令时发生此错误，但在rest.datasource.ts文件中保存更改后，webpack编译并运行应用程序

Answer 1

您的方法sendRequest会返回几种类型：

Observable<Product | Product[] | Order | Order[]>

在您的组件中，您可能声明了一个变量，它将保存结果：

myvar: Product[];

但你应该做的是

myvar: Product | Product[] | Order | Order[];

您的错误来自于您的变量可以包含多种类型的数据，但您只能覆盖一种。

执行Angular4应用程序构建时出错TC2322

1 个答案: